I did some concept drawings for Jane and Bella.

My thought process was to let Jane be a little more organic and simple. As Nyte said: she is the normal gym leader and being a dancer likely wouldn't be wearing too much. Her half of the Rivalry orb in on a necklace. She has a long, tunic thing that I'd probably make beige, and black leggings.
Bella I tried to put into a structured jacket, as well as a tunic similar to Jane's underneath. Her half of the Rivalry Orb is pinned to her jacket. I didn't have any ideas for her pants and shoes, so I went generic for this first draft.

They are meant to be pretty opposite. Jane's clothes are simple, while Bella's are more complicated. But there are still similarities, as though they were once friends who had a falling out.